Gene Transfer Relieves Diabetes

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Gene Transfer Relieves Diabetes

A gene therapy technique shows new promise in treating people with diabetes by making the liver produce insulin.

Researchers have successfully transferred insulin-producing genes, called PDX-1, into the livers of mice, increasing their levels of insulin -– the blood-sugar controlling hormone normally manufactured by the pancreas. The mice treated with the gene therapy had three times more insulin in their blood than untreated diabetic mice.

"These results could constitute a breakthrough in the prospects of therapy for type 1 diabetes," said Axel Kahn, of INSERM in Paris, in a Nature Medicine commentary on the research. Both the research and the commentary were published in the May issue.

"Considerable efforts will be needed to fully characterize the events triggered in the liver by expression of PDX-1," Kahn added.

The release of insulin spared the animals from the effects of high blood sugar. All of the mice that received the gene therapy survived throughout the experiment and showed gradually decreasing blood sugar levels. Of 22 untreated diabetic mice, 12 died within several days, and they all died within 8 days after the researchers induced diabetes using a chemical called streptozotocin.

Type 1 diabetes is caused by the failure of pancreatic cells to produce insulin. Researchers continue to work on ways to transplant or replace pancreatic tissue to treat diabetes. This latest approach uses a gene therapy technique that involves using an altered virus to carry the gene in to the liver.

Gene therapy has become a controversial procedure in recent months after the first death caused by the technique happened last September at the University of Pennsylvania. However, just last week, researchers at the Necker Hospital in Paris reported hopeful results. Two young boys with SCID-X1, an immune system disease that required them to live in sterile "bubbles," were successfully treated for one year, and they continue to do well, living normal lives.

Although researchers say more research is needed, the results of the mouse study suggest that the technique is promising.

The authors said that the PDX-1 gene transfer technique reprograms tissues other than the pancreas to produce insulin in a way that can effectively control abnormally high blood sugar levels.

The gene could be working in two ways, Kahn said in the commentary. It either activates the insulin gene in the liver producing the hormone in low levels. Or in some cases, PDX-1 might convert the liver cells to pancreas-like cells that produce insulin and release it according to blood sugar levels.